The invention is based on a circuit arrangement for the approximate linearization of the output signal of hot-wire probes. This output signal is in an approximate parabolic correlation with the rate of air flow in the intake manifold of an internal combustion engine, and a squaring of the output signal serves for an approximate linearization. However, since the correlation between the rate of air flow and the probe output signal has only an approximate parabolic configuration, the linearizing process carried out in the circuit arrangement of the prior art is deficient, whereby errors can occur during the processing of the probe output signal.